Hi Sina-

From what you've described, the distinguishing feature you and your friend have is that you decorate cakes really well. Having a store that sells the supplies isn't taking advantage of the talent you already have. It may be a better idea for you to concentrate on selling your cake decorating skills rather than opening a store to sell supplies.

Also, realisticly, the market for decorated cakes is probably bigger than it is for decorating supplies. So, you're more likely to succeed.

Good luck!

~~~~~~~~~~~